I have a fully redundant HP 8/20q FC SAN that has been working well, but as I dig deeper into things looking for more performance, I'm quickly at the end of my knowledge when it comes to FC topologies.
The SAN is comprised of three dual-port hosts, two switches, and two dual-controller+port arrays (each array is a HP P2000 G3 MSA, has two controllers, and each controller has two FC ports). Each host is connected to both switches, and one port on each array controller is in each switch. The round-robin access strategy is active/active ULP.
As I understand it, the hosts should connect to the switches in F_PORT (p2p/fabric) mode, and not FL_PORT (loop) mode, but what about the arrays? What are the practical differences between the two in terms of redundancy and performance? Each switch has a single port from the MSA logged in as a loop device.
I can change the modes easy enough, without replugging anything. What I'm looking for is a good reason to choose one over the other. I have been operating under the assumption that there really is no point to ever using loop mode, as that's what "everyone says", but I'm don't understand why -- are there no good reasons to use loop in situations that don't require it, period?